下限界応力拡大係数 K_<ISCC> の AE による評価

概要

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In this paper, a new method to evaluate the threshold stress-intensity factor K_<ISCC> by the use of acoustic emission (AE) signal analysis is proposed using the material of type 4340 steel, of which hydrogen content was controlled by the cathodic electrolytic method. In the subcritical crack growth due to hydrogen embrittlement, a linear correlation was observed between stress-intensity factor K and emission event counts N. From this relation K_<ISCC> was defined as a stress-intensity factor K_<AE> corresponding to the generation of AE events. The effects of K and threshold voltage of AE measurement on the K_<ISCC> were discussed in detail, and with the results of fractography it was concluded that the obtained K_<ISCC> corresponded to the nucleation of hydrogen induced intergranular microcrack in the maximum triaxial stress field ahead of the crack tip.
社団法人日本鉄鋼協会の論文
1981-08-01